SELENIUM RPD250X -Watt -Channel Studio Subwoofer, Features - Innovative smooth EVA foam surface Safety-rated for all ages Oversized 14 14 tiles means extra-large play space Customize the size use 4 tiles or all 20. Even add more sets Oversized 14 14 tiles means extra-large play space Customize the size use 4 tiles or all 20. Even add more sets